Low birth weight risk reduction continues to be a challenge for health care professionals. Tobacco smoke exposure during pregnancy is a modifiable risk that can improve LBW rates. The purpose of this research is to determine the effectiveness of the Smoke Free Families smoking cessation intervention. The desired outcomes are that pregnant smokers move forward in the stages of becoming a non-smoker and that household environmental tobacco smoke (ETS) exposure is reduced. A two group longitudinal randomized study will be conducted with 200 families who are HMO members. Half of the families will constitute the control group and will receive the usual HMO care. The other 100 families will participate in the experimental program, Smoke Free Families (SFF). Smoke Free Families is tailored to pregnant women and their families. The intervention includes stage of change matched activities, methods to enhance perception of the fetus by women and family members, and support for the development of a plan to eliminate ETS from the household. The research aims are to: a) determine, over three month period the program's effectiveness in achieving the outcomes of moving pregnant women forward in the stages of becoming nonsmokers and reducing women's exposures to household ETS; b) determine the relative contributions of group membership, processes of change, self-efficacy, and family support to the outcomes of moving toward becoming a non-smoker and decreasing household ETS exposure; c) describe patterns of women's smoking cessation attempts and degree of implementation of ETS control during pregnancy; d) evaluate women's uses of processes of change, perceptions of self-efficacy, and feelings of family support as a response to the experimental program; e) evaluate families' perceptions of usefulness and desirability of program activities. Interview, questionnaire and biologic marker data collection data procedures will be used. Interview data include smoking status, movement in the stages of change, and ETS exposures. Questionnaire data include processes of change, self-efficacy and family support. Smoking cessation attempts will be biochemically confirmed using the biological marker, urine cotinine. Qualitative evaluative data will be obtained by interview from women and family members. Quantitative data will be analyzed using Chi-square, analysis of covariance, regression and discriminant analysis. Qualitative data will be analyzed using thematic analysis. Results will be used to refine and further develop the Smoke Free Families intervention for a subsequent large scale study.